The skin is an essential component of the nonspecific immune system and functions as a first barrier to pathogenic infection. Breaches in the skin, i.e., wounds, predispose the patient to infection. Thermal burns cause massive destruction of the integument as well as suppression of humoral and cellular immunity, enabling opportunistic organisms that do not generally infect a healthy person to infect a burn victim, both topically and systemically. Scratches, bites and ulcers also cause infection by allowing the introduction of microorganisms into deeper, susceptible tissues.
Each year, approximately 2.4 million Americans are burned. Physicians treat about 650,000 of the burn victims, 75,000 of these patients require hospitalization, and 12,000 die of burns. One million people each year sustain substantial temporary or permanent disabilities resulting from burn injuries. Infectious complications are the leading cause of morbidity and mortality in serious burn injury, with approximately 10,000 patients in the U.S. dying of burn-related infections each year. When skin is damaged or missing due to burns, trauma or toxic injury, the mechanical functions of the skin must be replaced promptly to provide an environment that will optimize cellular regeneration and minimize the chance for sepsis. During this healing process, systemic immunosuppression is induced, placing the patient at greater risk for infection. Burns also predispose the affected area to infection by damaging the protective barrier function of the skin, thus allowing the entry and colonization of opportunistic organisms.
An ultimate goal of burn wound management is closure and healing of the wound. One way in which wound healing is promoted is the use of dressings to cover the wound site. An ideal dressing is one that flexibly covers the wound site and provides a barrier to infectious organisms and an environment that promotes the healing process. A preferred environment is one similar to the patient's own skin in providing a moisture retaining, germ resistant covering while possibly stimulating the healing. Although biological dressings, e.g., porcine xenografts, have been the dressing of choice since the early 1960's, new synthetic dressings are being introduced that have the additional benefit of being sterile. Both biological and synthetic dressings serve as temporary coverages for wounds and essentially all provide a barrier that aids in healing.
Burn wound healing has traditionally been augmented by the use of topical antibiotics. Currently, the most common antimicrobial agents used for burn victims are silver sulfadiazene cream, mafenide acetate cream, and silver nitrate, which dramatically decrease the bacterial burden of burn wounds and consequently decrease the rate of infection. These compounds, although effective, have limitations. Silver sulfadiazene is often used initially, but its value is often limited by bacterial resistance. Mafenide acetate is more broad spectrum in effect but it has negative side effects such as metabolic acidosis and hypersensitivity.
Other wounds can also be problematic for the treatment of antibiotic infection, especially wounds that are more likely to expose a subject to infectious agents (e.g., an animal bite), or wounds that are deep and/or difficult to access (e.g., puncture wounds). Animal bites, including human bites, expose the damaged tissue to a variety of pathogens that reflect the oral flora of the biting animal. Antibiotic management of wounds such as animal bites and puncture wounds is thus challenging, since the antibiotics used depend in large part on the potential pathogens that may have infected the wound. This can be especially problematic in individuals with antibiotic allergies, e.g., penicillin allergies, since treatment for these patients may require combination therapies to provide broad spectrum protection. In addition, certain animal bites, such as snake bites, also can result in severe inflammatory responses and/or tissue necrosis, which renders these bites especially prone to infection.
There is a need in the art for devices to promote healing and prevent infection in burns, bites, and other skin lesions that simultaneously provide a physical barrier and a chemical treatment for prevention of infection to aid the healing process. There is also a need for sterile methods of closure that can provide additional antibiotic protection to these wounds.